.\"	$OpenBSD: mem.4,v 1.2 2007/05/31 19:19:55 jmc Exp $
.\" Copyright (c) 1992, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This software was developed by the Computer Systems Engineering group
.\" at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
.\" contributed to Berkeley.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
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.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\"     from: @(#)mem.4	8.1 (Berkeley) 6/5/93
.\"
.Dd $Mdocdate: May 31 2007 $
.Dt MEM 4 luna88k
.Os
.Sh NAME
.Nm mem ,
.Nm kmem
.Nd memory files
.Sh DESCRIPTION
The file
.Pa /dev/mem
is an interface to the physical memory of the
computer.
Byte offsets in this file are interpreted as physical memory addresses.
Reading and writing this file is equivalent to reading and writing
memory itself.
An error will be returned if an attempt is made to reference
an offset outside of
.Pa /dev/mem .
.Pp
Kernel virtual memory is accessed via the file
.Pa /dev/kmem
in the same manner as
.Pa /dev/mem .
Only kernel virtual addresses that are currently mapped to memory are allowed.
.Pp
On the luna88k, physical memory is always contiguous;
kernel virtual memory begins at
.Ad 0x00000000 .
.Pp
Writeability of these devices is controlled by the system
.Xr securelevel 7 .
.Sh FILES
.Bl -tag -width /dev/kmem -compact
.It Pa /dev/mem
.It Pa /dev/kmem
.El
.Sh SEE ALSO
.Xr securelevel 7
.Sh HISTORY
The
.Pa /dev/mem
and
.Pa /dev/kmem
files appeared in
.At v6 .
